The Chicago Zoological Society’s Animal Welfare Research team is committed to ensuring that each and every Brookfield Zoo resident has the opportunity to thrive. While animal welfare is a priority for all facilities accredited by the Association of Zoos and Aquariums, most welfare research has centered on mammals. Indeed, despite the fact that zoos and aquariums house significantly more birds than mammals, less than 10% of the welfare studies published in our industry over the last decade focused on birds. Fortunately, the zoological community can expand our knowledge by learning from welfare scientists working with lab, companion, and farm animals. This year, our team published an article that summarizes key findings from these fields and highlights future directions for bird welfare research in zoological facilities.

So, how do we know if a bird is comfortable or possibly even content? Typically, we look for the expression of natural behaviors, such as nesting, locomotion (e.g. swimming, flying), preening, and dustbathing. If an individual engages in behaviors we would expect to observe in a natural setting, we assume that most of his/her needs are being met. Alternatively, if the animal is unable to display internally-motivated behaviors, the bird may be experiencing compromised welfare. It is our job to provide healthy, stimulating environments that promote good physical, mental, and emotional health and to regularly monitor welfare so we can intervene proactively, if necessary. Fortunately, we have several ways of assessing welfare, including non-invasively tracking physiological biomarkers (e.g. using droppings or feathers to measure corticosterone) and monitoring behavior (e.g. conducting observations, utilizing radio-frequency identification tags).
 
As the review article discusses, there are several factors or “inputs” we can consider as we strive to enhance the quality of life of individual birds, including: housing, flooring, lighting, the sound environment, social interactions, human-bird interactions, nutrition, and environmental enrichment. Some of these are straightforward. For example, in terms of housing, arboreal bird species are motivated to fly, water birds are motivated to swim, and many species are motivated to nest, so habitats should be designed and adapted accordingly. When it comes to flooring, we learned from the agricultural industry that providing poultry with deep litter (e.g. wood shavings, straw material) promotes good foot health, encourages physical activity, and stimulates natural behaviors such as dustbathing and foraging.

Research on poultry also has shown us how lighting can impact well-being. For instance, chickens exposed to longer dark periods are less likely to exhibit stress, negative emotional states, lameness, bone development issues, or impaired hormone cycles. Furthermore, due to the fact that birds have tetrachromatic vision, ultraviolet (UV) lighting may be essential in regards to mate choice, foraging, and obtaining information about the environment. It is also crucial to consider a bird’s sound environment, as ambient noise can interfere with communication and even impact an individual’s stress response and overall health. As you can imagine, in terms of promoting healthy social behavior, it can be tricky to replicate natural flock numbers in a zoo. Therefore, at the very least, we aim to determine the minimum number of birds per flock needed to achieve good welfare in gregarious species, such as penguins and pelicans. For instance, a large-scale study of great white pelicans found that individuals who lived in groups of ten or more birds exhibited lower corticosterone concentrations than those housed with less than ten individuals. Interactions with humans – both guests and keepers – must also be closely evaluated. In some cases, the presence of guests can be beneficial, as discovered for penguins who displayed increased behavioral diversity when guests were present. Finally, zoos and aquariums rely on nutritionists to create species-specific diets by investigating how: 1) the species metabolizes particular nutrients, and 2) nutrients affect behavior and health. As you can see, enhancing bird welfare is a team effort that involves examining numerous factors!
 
Fortunately, CZS has the expertise and resources needed to investigate how birds living at Brookfield Zoo (and beyond) can be positively impacted by modifying enclosures, adding substrates, adjusting lighting, controlling noise levels, providing opportunities for social interaction, promoting positive interactions with humans, and improving diets. Anyone who has strolled around the zoo recently knows we continuously strive to enhance our residents’ daily lives by offering environmental enrichment. For birds, we can install extra perches, present novel objects, increase the distance between feeders/drinkers, feed live insects, and add nest boxes/nesting materials to increase activity and stimulate natural behaviors. There is evidence from macaws and parrots that these sorts of enhancements have several positive effects, including stress resilience, more positive social interactions, less aggression, and improved feather condition.

One example of CZS staff working together to improve bird welfare comes from our Victoria crowned pigeons. By reviewing keeper assessments, we learned that feather condition improved and deteriorated seasonally. After our vets ruled out health and nutritional issues, we implemented an environmental tracking system to monitor humidity and discovered that feather condition worsened when humidity dropped below 35%-40%. Now, we can focus on identifying ways to increase humidity during the winter months. 

The next time you plan a trip to Brookfield Zoo, please visit our resident birds. While viewing their enclosures, keep your eyes peeled for nest boxes, substrates, and unique modifications!

Jessica Whitham, Ph.D.
Animal Welfare Biologist
Published October 7, 2022